Laminated shielding material and method for shielding an enclosure therewith

Abstract

A shielding system for an enclosure wherein strips of shielding material including a layer of metal, for example, metal foil or gauge metal, are placed on the walls of the enclosure in an overlapping or abutting relationship, with shielding tape between the overlapped portions or overlying the butted seam. The shielding tape preferably consists of an electrically conductive nonwoven mat of entangled fibers which is laminated on one side to metal foil and which is bonded on the other side to the metal substrates using nonconductive adhesive. The entangled fibers penetrate the nonconductive adhesive and contact the surface of the metal substrate to provide an electrical continuity that seals the seam against leakage of electromagnetic radiation.

We claim: 
     
       1. A system for shielding an enclosure, comprising first and second metal substrates having a seam therebetween, and means for sealing said seam to prevent leakage of electromagnetic radiation into said enclosure, said sealing means comprising a first electrically conductive nonwoven mat comprising randomly oriented and randomly packed fibers and a layer of nonconductive adhesive which penetrates said first nonwoven mat when not yet dried and which bonds said first nonwoven mat to said first metal substrate when dried, said penetration of said nonconductive adhesive allowing at least some of said fibers to contact the surface of said first and second metal substrates in said bonded state. 
     
     
       2. The shielding system as defined in claim 1, wherein said first and second metal substrates each comprise metal foil or gauge metal. 
     
     
       3. The shielding system as defined in claim 1, wherein said sealing means further comprises metal foil laminated to said first nonwoven mat. 
     
     
       4. The shielding system as defined in claim 1, wherein said fibers are made of electrically conductive material. 
     
     
       5. The shielding system as defined in claim 1, wherein said fibers are made of electrically nonconductive material coated with an electrically conductive material. 
     
     
       6. The shielding system as defined in claim 1, wherein said seam is a butted seam and said electrically conductive nonwoven mat of said sealing means overlies said butted seam. 
     
     
       7. The shielding system as defined in claim 1, wherein said seam is a lap seam and said electrically conductive nonwoven mat of said sealing means is between overlapping portions of said first and second metal substrates. 
     
     
       8. A system for shielding an enclosure, comprising first and second flexible strips of composite shielding material adhered to a wall of said enclosure with overlapping portions of said first and second flexible strips forming a lap seam, each of said flexible strips of composite shielding material comprising a metal substrate laminated to an electrically conductive nonwoven mat of randomly oriented and randomly packed fibers, said metal substrate of said overlapping portion of said first flexible strip opposing said nonwoven mat of said overlapping portion of said second flexible strip, and further comprising a layer of nonconductive adhesive which penetrates said nonwoven mat of said overlapping portion of said second flexible strip when not yet dried and which bonds said nonwoven mat of said overlapping portion of said second flexible strip to said metal substrate of said overlapping portion of said first flexible strip when dried, said penetration of said nonconductive adhesive allowing at least some of said fibers of said nonwoven mat of said overlapping portion of said second flexible strip to contact the surface of said metal substrate of said overlapping portion of said first flexible strip in said bonded state. 
     
     
       9. The shielding system as defined in claim 8, wherein said first and second metal substrates each comprise metal foil. 
     
     
       10. The shielding system as defined in claim 8, wherein said fibers are made of electrically conductive material. 
     
     
       11. The shielding system as defined in claim 8, wherein said fibers are made of electrically nonconductive material coated with an electrically conductive material. 
     
     
       12. A method for shielding an enclosure, comprising the steps of: applying a first sheet of shielding material comprising a metal substrate on a surface of said enclosure so that one side of said metal substrate of said first sheet is exposed;   applying a second sheet of shielding material comprising a metal substrate on said surface of said enclosure so that one side of said metal substrate of said second sheet is exposed, said first and second metal substrates being arranged to abut along respective edges thereof to form a butted seam;   overlying said butted seam along its entire length with electrically conductive nonwoven material comprising randomly oriented and randomly packed fibers;   applying a layer of undried nonconductive adhesive between said electrically conductive nonwoven material and said first and second metal substrates, said fibers of said nonwoven material penetrating said undried nonconductive adhesive and contacting the surfaces of said first and second metal substrates;   drying said nonconductive adhesive so that said electrically conductive nonwoven material is bonded to said first and second metal substrates with at least some of said fibers in contact with said surfaces thereof.   
     
     
       13. The method as defined in claim 12, wherein said first and second metal substrates each comprise metal foil or gauge metal. 
     
     
       14. The method as defined in claim 12, wherein said electrically conductive nonwoven material is laminated to metal foil. 
     
     
       15. The method as defined in claim 12, wherein said fibers are made of electrically conductive material. 
     
     
       16. The method as defined in claim 12, wherein said fibers are made of electrically nonconductive material coated with an electrically conductive material. 
     
     
       17. A method for shielding an enclosure, comprising the steps of: applying first and second sheets of shielding material on a surface of said enclosure, each of said first and second sheets comprising an electrically conductive nonwoven mat of randomly oriented and randomly packed fibers laminated to a flexible layer of metal, said first and second sheets being arranged to overlap along respective edges thereof to form a lap seam with a portion of said electrically conductive nonwoven mat of said first sheet opposing a portion of said flexible layer of metal of said second sheet;   applying a layer of undried nonconductive adhesive between said electrically conductive nonwoven material of said first sheet and said flexible layer of metal of said second sheet, said fibers of said nonwoven material of said first sheet penetrating said undried nonconductive adhesive and contacting the surface of said flexible layer of metal of said second sheet; and   drying said nonconductive adhesive so that said electrically conductive nonwoven material of said first sheet is bonded to said flexible layer of metal of said second sheet with at least some of said fibers in contact with said surface thereof.   
     
     
       18. The method as defined in claim 17, wherein said first and second flexible layers of metal each comprise metal foil. 
     
     
       19. The method as defined in claim 17, wherein said fibers are made of electrically conductive material. 
     
     
       20. The method as defined in claim 17, wherein said fibers are made of electrically nonconductive material coated with an electrically conductive material.